1. Field of the Invention
This invention relates to an evaporator for a refrigerator, and more particularly to a liquid filled evaporator of the shell and tube type which is adapted to be used for a refrigerator such as a turborefrigerator or the like which includes a refrigerator driven as a heat pump as well.
2. Description of the Prior Art
A typical liquid filled evaporator of the shell and tube type which has been conventionally used is disclosed in Japanese Patent Application Publication No. 11630/1967 and Japanese Patent Application Laid-Open Publication No. 30059/1978. The conventional evaporator taught in the publications includes a cylindrical drum circular in vertical section in which a plurality of heat exchanger tubes are arranged.
The conventional evaporator of such construction will be described with reference to FIGS. 1 and 2 showing a refrigerator in which the evaporator is incorporated.
The refrigerator shown in FIGS. 1 and 2 is constructed in a manner such that gaseous refrigerant is compressed in a turbocompressor 100 and then fed through a discharge pipe 102 to a condenser 104 to be condensed into liquid refrigerant. The so-formed liquid refrigerant is then fed through a passage 106, an orifice 108 and a header box 110 to the lower portion of an evaporator 112 of which the overall shape is cylindrical. The evaporator 112 comprises a drum shell 114 circular in vertical section and an internal construction received in the drum shell 114. The internal construction, as shown in FIG. 2, comprises a distribution orifice plate 116 positioned at the lowermost portion of the interior of the drum shell 114, a distribution plate 118 positioned above the distribution orifice plate 116, a heat exchanger tube nest comprising a plurality of heat exchanger tubes 120 provided above the distribution plate 118, and a partition plate 122 and an eliminator 124 arranged in turn above the heat exchanger tubes 120. Also, the drum shell 114 is provided at the upper portion thereof with a suction pipe 126 connected to the turbocompressor 100. The drum shell 114, as shown in FIG. 1, is closed at both side ends thereof with tube plates 128a and 128b respectively provided at the lower portions thereof with leg members 130a and 130b. The heat exchanger tubes 120 each are supported at both ends thereof on the tube plates 128a and 128b and communicated at the both ends through the tube plates 128a and 128b with cool water chambers 132a and 132b, respectively. Also, the eliminator 124 is connected at both ends thereof on the tube plates 128a and 128b and closed with patches 134a and 134b, respectively.
In the conventional evaporator, the eliminator 124 is arranged above the heat exchanger tubes 120 at a distance or height H therefrom sufficient to substantially prevent the globules of liquid refrigerant accompanying the gas stream of the refrigerant ascending from the gas-liquid interface of the refrigerant due to the boiling of the refrigerant. Also, it is required to provide, above the eliminator 124, a space 136 sufficient to permit the evaporated refrigerant to be guided therethrough to the suction pipe 126 at an appropriate velocity.
Further, in the conventional evaporator, a plurality of the heat exchanger tubes 120 are arranged in the lower half of the interior of the drum shell 114 and supported at the intermediate portions thereof on a support plate 138.
The arrangement of the heat exchanger tubes 120 in the drum shell 114 is generally carried out in such a manner that the heat exchanger tubes 120 are gradually increased in number from the lowermost tube array to the uppermost tube array to prevent the heat exchanger tubes positioned at both ends of each tube array from contacting the inner surface of the drum shell 114.
However, in the conventional evaporator 112 having the drum shell 114 circular in vertical section, as described above, it is required to install the eliminator 124 at a predetermined height H above the gas-liquid interface of the refrigerant so as to prevent the globules of refrigerant from reaching the eliminator 124 and provide the space 136 above the eliminator which is sufficient to allow evaporated refrigerant to be introduced into the suction pipe 126 at an appropriate velocity.
In the conventional evaporator 112, any restriction due to the internal flow of refrigerant is not imposed on the lateral width dimension of the drum shell 114. Accordingly, when it is required to enlarge the vertical dimension of the the drum shell 114 for the reason as described above, the overall lateral dimension of the drum shell 114 is caused to be excessively extended because the drum shell 114 is generally formed into a circular shape in vertical section. This causes the overall drum shell to be excessively enlarged, resulting in the overall dimensions of the evaporator being substantially enlarged.
Further, in the conventional evaporator, the heat exchanger tubes are gradually decreased in number in the downward direction since the drum shell 114 is circular in vertical section. This results in the outer heat exchanger tubes in all of the heat exchanger tube rows but the lowermost one, or the heat exchanger tubes surrounded by chain lines 140 and 142 in FIG. 2, being not substantially affected by the distribution plate 118, so that refrigerant fails to be subjected to uniform and sufficient agitation at the sections 140 and 142, to thereby deteriorate heat exchanging at the sections.